// Copyright(c) 2019 ZVYAGIN.Alexander@gmail.com
// Distributed under the MIT License (http://opensource.org/licenses/MIT)

#pragma once

#include <spdlog/details/null_mutex.h>
#include <spdlog/details/os.h>
#include <spdlog/details/synchronous_factory.h>
#include <spdlog/sinks/base_sink.h>

#include <array>
#ifndef SD_JOURNAL_SUPPRESS_LOCATION
#define SD_JOURNAL_SUPPRESS_LOCATION
#endif
#include <systemd/sd-journal.h>

namespace spdlog {
namespace sinks {

/**
 * Sink that write to systemd journal using the `sd_journal_send()` library
 * call.
 */
template <typename Mutex> class systemd_sink : public base_sink<Mutex> {
public:
  systemd_sink(std::string ident = "", bool enable_formatting = false)
      : ident_{std::move(ident)}, enable_formatting_{enable_formatting},
        syslog_levels_{{/* spdlog::level::trace      */ LOG_DEBUG,
                        /* spdlog::level::debug      */ LOG_DEBUG,
                        /* spdlog::level::info       */ LOG_INFO,
                        /* spdlog::level::warn       */ LOG_WARN,
                        /* spdlog::level::err        */ LOG_ERR,
                        /* spdlog::level::critical   */ LOG_CRIT,
                        /* spdlog::level::off        */ LOG_INFO}} {}

  ~systemd_sink() override {}

  systemd_sink(const systemd_sink &) = delete;
  systemd_sink &operator=(const systemd_sink &) = delete;

protected:
  const std::string ident_;
  bool enable_formatting_ = false;
  using levels_array = std::array<int, 7>;
  levels_array syslog_levels_;

  void sink_it_(const details::log_msg &msg) override {
    int err;
    string_view_t payload;
    memory_buf_t formatted;
    if (enable_formatting_) {
      base_sink<Mutex>::formatter_->format(msg, formatted);
      payload = string_view_t(formatted.data(), formatted.size());
    } else {
      payload = msg.payload;
    }

    size_t length = payload.size();
    // limit to max int
    if (length > static_cast<size_t>(std::numeric_limits<int>::max())) {
      length = static_cast<size_t>(std::numeric_limits<int>::max());
    }

    const string_view_t syslog_identifier =
        ident_.empty() ? msg.logger_name : ident_;

    // Do not send source location if not available
    if (msg.source.empty()) {
      // Note: function call inside '()' to avoid macro expansion
      err = (sd_journal_send)("MESSAGE=%.*s", static_cast<int>(length),
                              payload.data(), "PRIORITY=%d",
                              syslog_level(msg.level),
#ifndef SPDLOG_NO_THREAD_ID
                              "TID=%zu", details::os::thread_id(),
#endif
                              "SYSLOG_IDENTIFIER=%.*s",
                              static_cast<int>(syslog_identifier.size()),
                              syslog_identifier.data(), nullptr);
    } else {
      err = (sd_journal_send)("MESSAGE=%.*s", static_cast<int>(length),
                              payload.data(), "PRIORITY=%d",
                              syslog_level(msg.level),
#ifndef SPDLOG_NO_THREAD_ID
                              "TID=%zu", details::os::thread_id(),
#endif
                              "SYSLOG_IDENTIFIER=%.*s",
                              static_cast<int>(syslog_identifier.size()),
                              syslog_identifier.data(), "CODE_FILE=%s",
                              msg.source.filename, "CODE_LINE=%d",
                              msg.source.line, "CODE_FUNC=%s",
                              msg.source.funcname, nullptr);
    }

    if (err) {
      throw_spdlog_ex("Failed writing to systemd", errno);
    }
  }

  int syslog_level(level::level_enum l) {
    return syslog_levels_.at(static_cast<levels_array::size_type>(l));
  }

  void flush_() override {}
};

using systemd_sink_mt = systemd_sink<std::mutex>;
using systemd_sink_st = systemd_sink<details::null_mutex>;
} // namespace sinks

// Create and register a syslog logger
template <typename Factory = spdlog::synchronous_factory>
inline std::shared_ptr<logger>
systemd_logger_mt(const std::string &logger_name, const std::string &ident = "",
                  bool enable_formatting = false) {
  return Factory::template create<sinks::systemd_sink_mt>(logger_name, ident,
                                                          enable_formatting);
}

template <typename Factory = spdlog::synchronous_factory>
inline std::shared_ptr<logger>
systemd_logger_st(const std::string &logger_name, const std::string &ident = "",
                  bool enable_formatting = false) {
  return Factory::template create<sinks::systemd_sink_st>(logger_name, ident,
                                                          enable_formatting);
}
} // namespace spdlog
